This change adds a new native backend to remove eventually the need to
depend on external skopeo binary.
Using the native library allows much better control and error handling.
It also enables us to add more easily new features like signing for
example.

* Migrate image inspect and copy into a interface
* Migrate skopeo based calls into new package
* Remove code duplication in registries
* Add cache layer backend
* Add new optional alternative native image backend

One central place to handle caching

add back secret to gh action

This reverts commit 1cf14ac.